5 | ORACLE EXADATA DATABASE MACHINE X7-2
We chose Oracle Exadata because it
offered a complete solution ... we’ve created
daily financial reports 4x faster and liquidity
risk reports 7x faster to consistently meet
our service
-level agreement, improved
credit risk management, and reduced our
data center footprint
.”
- Vaibhav Samant
Senior Vice President, IT
HDFC Bank Ltd.
None of the reports takes more than 10
-
4 hours before, now
it completes in 3 minutes. It sounds like un
-
.”
- Finance User
Turkcell
performance for much more data than fits directly into flash.
Flash Cache automatically caches frequently accessed data while
keeping infrequently accessed data on disk. This provides the performance of flash with
the capacity and
low cost of disk. The Exadata Smart Flash Cache uniquely
understands database workload
s and knows when to avoid caching data that the
rarely access or is too big to fit in the cache.
For example, Exadata doesn’t
cache I/Os caused by backups,
large table scans, or temporary results that will be
quickly deleted. In addition to
automatic caching, administrators can optionally provide
directives to ensure that specific tables, indexes, or partitions are preferentially
the flash cache. A single full rack Exadata Database Machine X7-2, with 8
High Capacity storage servers can achieve up to 350 GB per
second of analytic scan bandwidth from SQL
, and up to 4.8
Million random 8K read
I/O operations per second (IOPS) from SQL
, and 0.25 ms I/O latency at 2.7 Million
when running database workloads.
Exadata’s Smart Flash Cache is designed to deliver flash
-level I/O rates and response
times for data that is many times larger than the physical flash capacity in the machine
by moving active data into flash, while leaving cold data on disk. It
is common for hit
rates in the Exadata Smart Flash Cache to be over 9
5%, or even 99% in real-world
database workloads even though flash capacity is more than
4 times smaller than disk
capacity. Such high flash cache hit rates mean that Exadata Smart Flash
Cache
effective flash capacity that is many times larger than the physical flash.
For example, a full rack Exadata Database Machine
X7-2 with 8 database servers and
14 High Capacity Storage Servers often has an effective flash capacity equal to
the
disk capacity of 500 TB.
The Exadata Smart Flash cache also caches database block writes using Exadata Write
Back Flash Cache technology. Write caching eliminates disk bottlenecks in large scale
OLTP and batch workloads. The flash write capacit
y of a single full rack Exadata
X7-2 with 8 database servers and 14 High Capacity Storage Servers
4.3 Million 8K write I/Os per second. The Exadata write cache is transparent,
persistent, and fully redundant. The I/O performance of
the Exadata Smart Flash Cache
is comparable to dozens of enterprise disk arrays with thousands of disk drives.
The automatic data tiering between RAM, flash and disk implemented in Exadata
provides tremendous advantages over other flash
-based solutions. Many storage
vendors have recognized that the architecture of their traditional storage arrays
inherently bottleneck the performance of flash and therefore have developed new flash
-
-only arrays deliver higher performance than traditional arrays
but give up the cost advantages of smart tiering of data between disk and flash.
Therefore the overall size of data that benefits from flash is limited to the size of
expensive flash. These flash arrays also do not benefit from any of Exadata’s
unique
storage optimization technologies. Data deduplication provided by some flash arrays is
very effective for VDI (Virtual Desktop Infrastructure) environments but is ineffective for
databases.
Exadata not only delivers much more capacity than generic
all-flash arrays, it also
delivers better performance. Flash
-only storage arrays cannot match the throughput of
Exadata's integrated and optimized architecture with full InfiniBand based scale
-out, fast
PCI flash, offload of data intensive operations to st
orage, and algorithms that are